The broad, long term objective of this application is to provide a markedly less expensive, minimally invasive treatment for low back pain arising from intervertebral disc pathology. The specific alms are: 1) to design pressure-active and biocompatible viscoelastic protein-based polymers i) to effect proper intra-disc pressure development on implantation in the nucleus pulposus for mechanical restoration of the compressed disc to its correct dimensions and internal pressure and ii) to stimulate tissue reconstruction for structural restoration of the intervertebral disc to its more natural state, 2) to evaluate the diseased state of human cadaver lumbar spines and to select appropriate diseased states for implantation of bioelastic polymers, 3) to perform mechanical studies on the selected lumbar spine segments (L1-L5) to assess efficacy of implanted viscoelastic protein-based polymers in restoring proper mechanical properties to diseased intervertebral discs, 4) to genetically engineer four specially designed bioelastic polymers for production by microbial biosynthesis, and 5) to plan in vivo animal model studies using the four designed bioelastic polymers in Phase II wherein injured intervertebral discs could be studied for efficacy of designed bioelastic polymers to restore the normal state. Success could, annually in the U.S. alone, return millions to work and reduce health care costs by tens of billions of dollars. PROPOSED COMMERCIAL APPLICATIONS: Low back pain, for which intervertebral disc pathology is the major cause, is second only to the common cold for work absenteeism in the United States; it is reported to result in more productivity loss than any other medical condition and a health care cost of $33 billion dollars/year. Over 4 million cases of prolapsed intervertebral discs are reported annually in the U.S. Development of materials to restore diseased intervertebral discs would be of commercial significance and would impact favorably on medical care costs.